Date of Graduation
Statler College of Engineering and Mineral Resources
Chemical and Biomedical Engineering
Rakesh K. Gupta.
This work was directed at improving the strength and durability of pultruded composites. Pultruded composites are being used in an increasingly wider range of applications, and, as a result, a higher demand has been placed on the performance capabilities of the various components.;One target area for improving composites is the fraction of voids in the final product. The presence of voids in a composite decreases the Interlaminar Shear Strength, provides a site for the formation of fractures, and increases the susceptibility of the part to outside contaminants.;In this work, the various steps of the pultrusion process are analyzed in order that the fraction of voids can be reduced. The goal is to promote uniform resin flow through the glass fibers, while the part is still in the die; this is because increasing resin flow in the die should result in fewer voids in the final product.;To achieve this objective, an existing pultrusion process was analyzed by modeling fluid mechanics, heat transfer and the chemical reactions involved in this process. From the results obtained, three conclusions could be drawn: (1) While pultruding at relatively low processing speeds, changes in processing speed do not have a significant influence in the final void fraction. (2) Void formation is suppressed by operating at the highest pull speed possible, without the exotherm being outside the end of the die. (3) A moderate variation in the temperature of the die will have a negligible impact on the void fraction of the component.;The void fraction of representative composite samples was measured with optical and scanning electron microscopy, and the results validated the above conclusions.
Freed, Adam Douglas, "Modeling the pultrusion process to obtain low void fraction composites" (2002). Graduate Theses, Dissertations, and Problem Reports. 1267.